Do Air Filters Have to be the Exact Size?

When it comes to air filters, it's important that they fit securely without having to force them into position. Learn more about how to find out what size air filters you need.

Do Air Filters Have to be the Exact Size?

When it comes to air filters, you want to make sure that it covers the duct opening. Measure the height and width of the duct opening and allow some overlap if you have space. This will be the exact size you need to order for your new air filter. It is important to note that there is no need for a hermetic seal between the frame and the air cleaner.

However, it should be quite tight with a small amount of space around the edges. If you need to force the filter into place, you probably need a different size. The goal is for the filter to slide comfortably in the frame with a little wiggle room, but not too much. Oven filters must fit securely, but there is no need to force them into position. If you have to force the filter into its slot, it's probably too big.

Forcing an incorrect filter size on a filter can cause it to bend, damage the filter, or reduce its ability to function properly. The filters are smaller than their slot to allow for easy replacement. Some HVAC units may need a filter with unique or unusual dimensions. In these cases, you need to order a custom filter. Most major retailers, such as Walmart, Target, and Home Depot, offer air cleaners, albeit with a different variety of options and brands to choose from.

You can find the recommended filter size for your unit model in the table titled “Find your air conditioner and oven filter by make, model number and size”.In addition, if there is any resistance to airflow caused by the use of a filter that is not the correct size, it can cause unnecessary stress on the HVAC unit itself, which could damage the system equipment and increase your energy bills. The easiest way to identify the size of the AC filter is to remove the existing filter from its slot and examine the filter frame. When making your purchase, you should order the filter by its nominal size, rather than its actual size. The number is then generally rounded up and used to label air filter packs; this measurement is called Nominal Size. However, you can choose not to use factory-installed filter grids and have an HVAC professional install an external filter grid to get a coarser filter.

To ensure that the next filter you purchase is the correct size for your system, you should measure the inside dimensions of the air cleaner inlet. The filter should be slightly smaller on each side of the filter housing slot, allowing you to slide the filter in and out with ease. Still, understanding the most common air filter size can be difficult if you're not sure what the numbers mean. Installing several 1-in-a-slot air filters, for example, can cause costly damage to your air conditioning unit, as residential ovens are not equipped to handle this level of airflow restriction. However, they usually add an additional surcharge to the filter to compensate for the services they provided.

In these cases, you have more flexibility in selecting the size of the filter since you can choose one that is longer than the size of the opening. If you can't find your size in store or need a custom-made air filter, online retailers are probably your best option. To ensure that your AC unit runs smoothly and efficiently without any issues related to incorrect sizing of filters, make sure that you measure your duct opening accurately before ordering a new air filter.